FreeOrion

FreeOrion is a strategy game released in an unknown date designed and developed by FreeOrion project. FreeOrion can be described as a free, open source game and can be played on the following operating systems: WindowsMac OSXLinux.
FreeOrion is also a multiplayer game.FreeOrion is a remake of an old video game.

“FreeOrion is a free, open source, turn-based space empire and galactic conquest (4X) computer game being designed and built by the FreeOrion project. FreeOrion is inspired by the tradition of the Master of Orion games, but is not a clone or remake of that series or any other game.” - FreeOrion project